1. Field of Invention
The present invention relates to a manufacturing method of a micro-lens substrate, a micro-lens substrate, an electro-optic device, an opposing substrate for a liquid crystal panel, a liquid crystal panel and a projection display device.
2. Description of Related Art
Currently, projection display device, that project images onto a screen are known. A liquid crystal panel is mainly used for creating the image. It is further known that some of the liquid crystal panels of this type have many tiny micro-lenses provided at the positions according to respective pixels of the liquid crystal panel for efficient utilization of light. These micro-lenses are usually formed on a micro-lens substrate that are included in the liquid crystal panel.
FIG. 12 shows a longitudinal section of a conventional structure of a micro-lens substrate used in a liquid crystal panel. As shown, micro-lens substrate 900 has a glass substrate 902 with many hemispheric concaves 903 and a cover glass 908 bonded to a surface, where the concaves 903 of the glass board 902 are formed via a resin layer 909. Also, in the resin layer 909, micro-lenses 904 are formed by a resin filled in the concaves 903.
Recently the progress and development of liquid crystal panels has advanced, and the quality of the images is remarkably good. As a result, it is often required that a liquid crystal panel with an extremely high contrast ratio and transmittance be developed to achieve even higher image quality. However, there is a limit to raise the contrast ratio and the transmittance in micro-lens substrate 900 having the structure shown in FIG. 12.
A purpose of the present invention is to provide a manufacturing method of a micro-lens substrate having a high contrast ratio and transmittance when used, for example, in a liquid crystal panel or the like.
A method for manufacturing a micro-lens substrate according to the present invention has the feature of bonding a first substrate having a plurality of curved lens surfaces and a second substrate having a plurality of curved lens surfaces to each other, thereby forming a plurality of microlenses consisting of double convex lenses.
The microlens substrate manufacturing method of the present invention has the further feature of bonding a first substrate having a plurality of first concave portions that have curved lens surfaces to a second substrate having a plurality of second concave portions that have curved lens surfaces via a resin so that the first concave portions and the second concave portions face each other, thereby forming a plurality of microlenses that consist of double convex lenses between the first and second substrates.
A more desirable micro-lens can be formed as follows. The curvature radius of the curved surface of lens of the first substrate and the curvature radius of the curved surface of lens of the second substrate are different. The curvature radius of the curved surface of the lens of the first substrate is greater than the curvature radius of the curved surface of the lens of the second substrate. The maximum thickness of the micro-lens is in the range of 10xcx9c120 micrometers. The focal length of the micro-lens is in the range of 20xcx9c1000 micrometers. A resin containing a spacer is placed on the outside of the region where the curved lens surfaces of the first substrate and/or the second substrate are placed, and the first substrate and the second substrate are conjugated. The spacer is particulate. Each alignment marker is provided on the first substrate and the second substrate, and the alignment of the first substrate and the second substrate is accomplished using the alignment marker and the first substrate and the second substrate are bonded to each other. The curved lens surfaces of the first substrate and the second substrate are made using a mask layer, and the alignment marks of the first substrate and the second substrate are formed using a mask layer.
The micro-lens substrate of the present invention is a micro-lens substrate with plural micro-lenses being arranged on the substrate, wherein the micro-lens comprises a double convex lens. The first substrate with plural concaves arranged on its surface and the second substrate are bonded to each other via a resin layer, and the micro-lens is formed by a double convex lens between the first substrate and the second substrate.
The first substrate with plural concaves being arranged on its surface and the second substrate with plural concaves being arranged on its surface are bonded to each other via a resin layer so that the concave of the first substrate and the concave of the second substrate face one another, and the micro-lens is made of double convex lens between the first substrate and the second substrate.
Preferably, the thickness of the resin layer in the region where the micro-lens is not placed is nearly the same as the Koba thickness of the micro-lens. The first substrate is thicker than the second substrate. The spacer is arranged to define the thickness of the resin layer on the outside of the region where the micro-lens is placed. The spacer is particulate. The curvature radius of curve surface on the light-incident side of the micro-lens and the curvature radius of curve surface on the light-emergent side of the micro-lens are different from each other. In case of operation where light falls on the side of the first substrate, the curvature radius of curve surface on the light-incident side of the micro-lens is greater than the curvature radius of curve surface on the light-emergent side of the micro-lens. The maximum thickness of the micro-lens is in the range of 10xcx9c120 micrometers. The focal length of the micro-lens is in the range of 20xcx9c1000 micrometers. Alignment marks as an indicator for aligning are provided outside of the region where the micro-lenses are formed.
The opposing substrate for a liquid crystal panel according to the present invention can have a micro-lens substrate, a black matrix arranged on the micro-lens substrate and an electro-conductive layer covering the black matrix.
A liquid crystal panel according to the present invention can include a liquid crystal drive substrate with a pixel electrode, and an opposing substrate for a liquid crystal panel bonded to the liquid crystal drive substrate and a liquid crystal filled in the gap between the liquid crystal drive substrate and the opposing substrate for a liquid crystal panel. Preferably, the liquid crystal drive substrate is a TFT substrate having pixel electrode arranged like a matrix and a thin film transistor connected to the pixel electrode.
The projection display device has light valves having a liquid crystal panel, and it modulates light using at least one of the light valves and projects images.